In recent years, expectations are running high for magnetic refrigeration that is one of environmentally friendly refrigeration technologies with a high refrigeration efficiency, and research and development of magnetic refrigeration technologies in a room temperature range is being actively conducted.
As one of the magnetic refrigeration technologies, an AMR (Active Magnetic Regenerative Refrigeration) method has been proposed. The AMR method positively utilizes lattice entropy that is regarded as an inhibitory factor for magnetic refrigeration in the room temperature range. A magnetic body is thus caused to have the function of performing a magnetic refrigeration operation by a magneto-caloric effect and simultaneously provide a heat storage effect of storing cryogenic energy generated by the magnetic refrigeration operation.
In a representative AMR apparatus, for example, a heat-exchanger fluid such as water circulates through a magnetic container filled with particulate magnetic bodies. The heat-exchanger fluid is reciprocally moved in synchronism with application and removal of a magnetic field to and from the magnetic container, respectively, thereby implementing a refrigeration cycle.
In the AMR refrigeration cycle, no compressor is necessary, and a little power suffices. For this reason, a high refrigeration efficiency is expected to be attained as compared to, for example, a conventional refrigeration method by a compression cycle using CFC.